某公路弱膨胀土土水特征与非饱和渗透特性

Soil-water Characteristics and Unsaturated Permeability Coefficient Related to Weak Expansive Soils of a Certain Highway

文章对湖北某高速公路某高路堑边坡弱膨胀土的土-水特征进行了试验研究,吸力量测采用气相法与渗析(液相)方法,并获得了吸力范围为0.01～309MPa的土-水特征曲线;并根据Fredlund和Xing的对数函数形式表达的数学模型对试验结果进行了拟合分析;在此基础上,利用Childs等人建立并多次修改的预测模型,预测了试验土样的相对渗透系数。土样土-水特征曲线的减饱和过程具有明显边界效应段和过渡段,但残余段不够明显,其非饱和相对渗透系数随吸力(含水量)变化呈非线性变化,吸力增加(含水量降低)渗透性快速降低。

A laboratory test on soil - water characteristics has been carried out on certain weak expansive soils, which was obtained from a high slope along a highway in Hubei province. The osmotic technique and the vapour phase technique were employed for suction control. And the water retention curve （ 0.01 - 309MPa ） was obtained of the tested soil. And then, the water retention curve for tested weak expansive soil was fitted according to the model proposed by Fredlund and Xing. Based on this, the coefficients of permeability were determined from this characteristic and the Childs and Collis - George model which is based on the random variation of pore size. The results show that the desorption curve of the specimen has significant boundary effccting segment and transition segment, whereas the residual segment is unobvious. The permeability of Hubei weak expansive soil varies nonlinearly with suction （ water content ）, and it decreases quickly with increasing of suction （ decreasing of water content ）.